This invention relates to aromatic heterocyclic polymers.
High temperature resins presently available have various drawbacks which limit their use in many applications. A serious one frequently encountered is the evolution of volatiles during the curing cycle, which makes it imperative that the entire curing cycle be carried out under pressure. For example, polyimides when cured release volatile components which cause gas bubble or void formation in the cured resin unless considerable pressure is maintained during the curing operation in order to prevent these undesirable results. When phenolic resins are cured, water is released which also causes void formation unless the curing reaction is carried out under pressure.
Acetylene-terminated compounds show promise for use in the preparation of matrix resins and adhesives for advanced aircraft and aerospace systems, and for other high-temperature applications. These compounds can be polymerized thermally without the evolution of volatile by-products, thereby obviating the problem of void formation in composite structures and molded articles.
Although many of the aromatic, heterocyclic, and aromatic/heterocyclic polymers exhibit superior mechanical and thermal properties, many of these polymers exhibit the disadvantages that they are soluble only in polar solvents, generally strong acids, which is a disadvantage from a processing standpoint.
It is therefore an object of the present invention to provide polymer systems having improved solubility characteristics.
It is another object of the invention to provide polymer systems which exhibit the desired superior physical properties as well as the required high degree of thermal stability.
Other objects and advantages of the invention will be apparent to those skilled in the art upon consideration of the following disclosure.